Underreamer.



.I. F. CRAVEN- UNDERREAMER.

APPLICATION FILED FEB. 19. 1915.

Patented Mar. 28,1916.

2 SHEETS-SHEET l- FIGJI INVENTOR 3 M WITNESSES .6 7 Fi/ zg FIGA x\ A 6 2 e5 N. UNDERREAMER. ICATION FILED FEB. 19, 1915 1,177,172. m I Patented Mar 1916.

was

55 i 3 socket 4 to hold the operating mechanism JAMES F. CRAVEN, OF GRAFTON, PENNSYLVANIA.

Specification of Letters Patent.

UNDEBREAMER.

Patented Mar. 28, 1916.

Application filed February 19, 1915. Serial No. 9,406.

- To all whom it may concern Be it known that 1, JAMES F. CRAVEN, a resident of Grafton, in the county of Allegheny and State of Pennsylvania, have invented a new anduseful Improvement in Underreamers, of which the following is a specification.

This invention relates to underreamers such as are used in well drilling for enlarging, below the end of the Well casing, the hole already formed.

The objects of the invention are to provide a simple and eiiicient underreamer which can be manufactured and assembled at comparatively low' ccst, in which all of the interior mechanism can be readily removed for inspection, repair or replacement, which is automatic in operation, in which the cutting bits are positively held or locked in their extended or cutting position and are solidly backed by the tool body so as not to impose upon the more delicate operating parts the heavy strains and jars of service, and which also is completely inclosed or free of exposed open'ngs, thereby prevent ing the access of rock fragments to the working parts and the possibility of choking or locking the tool and thus making it inoperative or preventing its withdrawal from the hole.

The invention compr ses the underremner hereinafter described and claimed.

In the drawings, Figure 1 represents a side elevation of one form of underreamer constructed according to the invention; Fig. 2 is a longitudinal sect onal View, on a larger scale, and taken on the line 2-2, Fig. 1; Fig. 3 is a similar view, taken on the line 3-3,.Fig. 2. and showing the cutting bits extended; Fig. 4 is a similar view showing the cutting bits retracted; Fig. 5 is a cross section on the curved section line 5-5, Fig. 3; Fig. 6 is a perspective view of a cover or roof for closing or sealing the cavity for the working parts; Fig.7 is asimilar view of a locking device; Figs. 8 and 9 are detail sectional views on the lines 8-8 and 9-9, Fig. 5, showing the mechanism for operating the locking device.

The underreamer shown in the drawings comprises a preferably cylindrical body 1 having the usual pin or tang 2 at one end, and provided intermediate its ends with a suitable wrench hold 3. The other end of the body is provided with a cavity or .bar on which the cutting bits turn.

and the shanks of the cutting bits. Said cavity has a semicylindrical bottom surface 5, two opposite side walls or surfaces 6, which may be straight and parallel but are shown as slightly diverg ng, and two opposurface 5 at the bottom of the cavity 4: are

struck around the aXis of the pintle 9 as a center or axis.

The cutting bits 10, of which there are two, have shanks 11 lying in the socket or cavitv at, said shanks being each of a thickness less than one half of the diameter of the cavity 4 between its diverging walls 7 to permit relative movement between said bits in extending and retracting the same. Each shank at one end is provided'with a round ear 12, said ears being perforated. as at 13, to receive the hinge pintle 9. The outer cylindrical surfaces of said ears fit the curved surface 5 at the bottom of the cavity a, so that the cutt'ng bits are solidly backed by the body of the tool and shocks or jars on said cutting bits are transmitted to the tool body and do not produce a shearing effect upon the hinge pintle 9. For the same reason the cutting heads 14. of the bits are larger than the shanks to thereby provide shoulders 15 on said heads, which shoulders are seated against and slide on the curved cylindrical end surface of the body portion of the tool, as shown in Figs. 3 and at.

The cutting bits are normally held in ex tended positionin any suitable manner, as by one or more springs 16,shown as spiral compression springs, whose ends are located in cavities in the adjacent faces of the shanks of the cutting bits. Suitable means is also provided .for positively locking said cutting .bits in extended position, so that said bits cannot be retracted without first operating the locking device. This locking device is shown in detail at 17 in Fig; 7. It comprises a bar having cvlindrical end portions or trunnions 17 which lie in the semicylindrical' bottom portions of cavities 18 in the side walls 6 of the tool body, and which are held therein by projections 19 located near the ends of a roof or cover member 20 having longitudinally extending end portions 21 fitting in shallow seats or sockets 22 in the side walls 6. The outer surface of the roof or cover member 20 is a little wider than the distance between the adjacent edges 23 at the bases of the heads of the cutting bits when extended, as shown in F 3, and the shanks of said bits are cut away at the bases of the heads thereof, as shown at 2st, to form a cavity to receive said roof or cover when said bits are retracted, as shown in Fig. 4. In both positions the cutting bits form retainers to hold the roof or cover in its seat and prevent escape there of, but when the bits are released from the tool, as hereinafter described, the roof or cover 20 removable therewith, as will be readily understood.

The intermediate locking portion 25 of the locking member has a cross section which is longer in one direction than in the other. Said member can be turned into either of two positions, as shown in Figs. 3 and In Fig. 3, the longer dimension of the locking portion 25 of the device is transverse to the length of the tool, so that said device effectually prevents any movement of the cutting hits toward each other. In Fig. 4: the locking device has been turned through an angle of 90 degrees, so that its shorter dimension is transverse to the length ofthe-cutting tool. In this release pcsition -the cutting bits have been moved toward each other into contact with the locking device, and are wholly within the limits of the cylindrical boundary formed by the outer surface of the body 1 of the tool.

The locking device 17 is so arranged as to always have a tendency to move to the looking position shown in F 8, so that whenever the cutting bits are extended said locking device turns to locking position and prevents retraction of the bits unless the locking device is first turned to the release position shown in Fig. t. For this purpose one or both ends of said locking device are reduced. as at 26, to receive .fiat coiled springs 27. the ends of which are secured to said locking device and to a convenient stationary point on the tool body, such as to the projections 19 on the roof or cover member 20.

Suitable means is also provided for rotating the locking device 17 against the resistance of sprin s 27 to release position, to thereby permit the cutting bits to be re tracted. In the tool shown in the drawings the locking device is operated by two oscillating members, marked 28 and 29, and shown in Figs. 8 and 9, and which members are locatednear the opposite ends of said locking device. These operating members 28 and 29 at one end are provided with annular ring-like portions 30 which surround and are ournaled upon reduced portions 81 at the sides of the cars 12 on the shanks of the cutting bits. The operating member 28 is provided with an external gear segment 32, the external teeth of which mesh with teeth 33 on one of the cylindrical end portions of the locking device 17. Operating member 29 is provided with an internal gear segment 34, the teeth of which mesh w'th teeth 35 upon the opposite cylindrical end portion of the locking device; Each operating member is provided with a laterally extending ear or lug 36, which ears or lugs. extend outwardly through openings in the opposite side walls 7 of the tool body, as shown in Figs. 1 and 5. Said ears or lugs are located behind the cutting bits 10 and therefore contact with the end edge of the well casing before the cutting bits 10 in removing the underreamer from the hole. The gear connections between said opera-ting members and the locking device are so ar- 'anged that either member, when swung inwardly toward the center of the tool. by pressing inwardly on its ear or lug 36, turns the locking device 17 from looking to rel ase position. Only one of said operating members is necessary, as the effect of both is the same, but two operating members are preferably provided as an additional safeguard and to also balance the torsion on the locking device and rotate it more readily to release position without material frictional resistance. When the tool is withdrawn from the hole the ears or lugs 36 first engage the end edge of the well casing to release the cutting bits, which in turn are moved inwardly or retracted by the engagement with the end edge of the well casing of their inclined rear surfaces 37. As the tool moves upwardly the cutting bits are withdrawn to the position shown in F in. 4': in which they lie wholly within the in boundaries of the outer surface of the to l. In this position their end cutting edges. 1n-

dicated at 38. are protected from injury by contact with protuberances within the well ca in because the extreme outer sun faces 39 of the cutting bits converge downwa dlv.

Fig. 8 in full li es shows the operating member 28 in locking position. It also indicates in dotted lines the release position of said locking member. in which position the curved end surface 40 adiacent the gear se ment 32 is in contact with the smooth cylindrical surface of the locking device. Said locking device consequently forms a stop or abutment to positively prevent the operating member from beingpushed in too far. Similarly, as shown in Fig. 9, the cylindrical surface at the opposite end of-the .lockingdevice forms an abutment which is contacted by the end wall 41 of the opening in the operating member 29 .to prevent it from being pushed in too far. I

,When the parts are in the position shown in Fig. 3 no pressure or force can directly move the cutting bits toward each other as r they are positively held apart by the locking device. When the locking device is rotated to release position, as shown in Fig. l, the cutting bits are still held in extended position by the springs 16, and if the locking device is operated by hand to insert the tool into the hole it is necessary to also manually retract the cutting bits to bring them within the boundaries of the outer surface of the moved to release position.

The underreamer described is entirely closed, or, in other words, has no exposed openings into which rock fragments might enter and thereby interfere with the operation of the tool. The head ends of the cutting bits overlie on three sides the end surfaces of the walls of the cavity in the end of the tool body, so that they very nearly cover completely the open end of said cavity. The space between the two cutting bits is fully closed by the roof or cover member 20, which is overlapped by both of the cutting bits even when in extended position. Consequently the end of the cavity in the tool body is completely closedat all times. The

only side openings in thetool body are filled by thehinge pintle9. Moreover, the tool ,bits are solidly backed by the tool body itself, both at the curved bottom 5 of the cav ity, and also where the shoulders 15 behind the heads of the cutting bitsabut the end edges of the side walls of the, cavity. Consequently, all the shock and jar of drilling is transmitted directly to the solid tool body and does not produce a shearing effect on the hinge pintle.

All of the parts of the tool can be readily removed for repair or replacement. For this purpose the hinge pintle 9 is provided with a transverse bore in which are located one or more yielding members, such as the two balls 42, which are pressed outwardly by a compression spring 43 therebetween, and which are prevented from escaping in any suitable manner, as by slightly peening over the edges of the transverse bore, as in dicated at M. These balls are located midway between the ends of the hinge pintle 9 and normally lie in an annular groove 45 located in the ears of the cutting bits. This construction enables the hinge pintle to be readily removed by merely pushing inwardly upon one end of the same, to thereby force the balls 42 toward each other in the transversebore of the hinge pintle and out of the annular groove 45. When the pintle operating parts, including the cutting bits, the springs 16, the operating members 28 and 29, the locking device 17, and the roof or cover member 20 can be removed end wise from the cavity inthe tool body. The operating parts are withdrawn in assembled condition in which they can be readily inspected and replaced without disassembling, if desired.

\Vhat I claim is i 1. An underreamer, comprising a body member having a cavity therein, swinging cutting bits located in said cavity and pro jecting through and working in openings in the end wall of the body member, and

-means forextending said bits, said bits be member having a cavity at one end thereof,

hinged cutting bits located in said cavity, spring means for extending said bits, and separate means in advance of the pivots for said bits for positively locking them in extended positicn.

3. An underreamer, comprising a body member having a cavity at one end thereof, hinged cutting bits located in said cavity, yielding means for extending said bits, and separate means located between said bits for positively locking them in extended position.

l. An underreamer, comprising a body memberhaving a cavity at one end, hinged cutting bits located in said cavity, means for yieldingly holding said bits in extended position, and separate rotatable means in advance of the pivots of said bits for positively locking them in extended position.

5. An underreamer, comprising a body member having a cavity at one end, hinged cutting bits located in said cavity, means for extending said hits, a hinge pintle for said bits removable through the side walls of said cavity, and yielding means carried by said pintle for normally holding the same in said body member.

6. An underreamer, comprising a body member having a cavity at one end, hinged cutting bits located in said cavity, and a rotatable locking device located between said bits for positively preventing retraction thereof.

7. An underreamer, comprising a body member having a cavity at one end, hinged cutting bits located in said cavity, a rotatable locking device for positively preventing retraction of said bits, and means for 1gperating said locking device to release the its.

8. An underreamer, comprising a body member having a cavity at one end, hinged cutting bits located in said cavity, a locking device for positively preventing retraction of said bits, and means located behind the cutting portions of said bits for operating said locking device to release the bits.

9. An underreamer, ccmprising a body member having a cavity at one end, hinged cutting bits located in said cavity, a locking device for positively preventing retraction of said bits, and means arranged to engage the end of the Well casing on Withdrawal of the tool from the hole for operating said locking device to release the bits.

10. An underreamer, comprising a body member having a cavity at one end, hinged cutting bits located in said cavity, a rotatable locking device for said bits having locking and release positions, and means for yieldingly holding the same in locking position.

11. An underreamer, comprising a body member having a cavity at one end, hinged cutting bits located in said cavity, a rotatable locking device for said bits having locking and release positions, means for yieldingly holding the same in looking position, and means for moving said locking device to release position.

12. An underreamer, comprising a body member having a cavity at one end, hinged cutting bits located in said cavity, and a locking device for said bits having its end portions journaled in the side Walls of the cavity and rotatable to locking and release positions.

13. An underreamer, comprising a body member having a cavity at one end, hinged cutting bits located in said cavity, a locking device for said bits having its end portions j ournaled in the side Walls of the cavity and rotatable to locking and release positions, and means for yieldingly holding said locking device in locking position.

14. An underreamer, comprising a body member having a cavity at one end, hinged cutting bits located in said cavity, a locking device for said bits having its end portions journaled in the side Walls of the cavity and rotatable to locking and release positions, means for yieldingly holding said locking device in locking position, and means located behind the cutting portions of said bits for rotating said locking device 'torelease position.

15. An underreamer, comprising a body member having a cavity at one end, hinged cutting bits located in said cavity and partially covering the open end thereof, means for extending said bits, and a member located between said bits for Wholly closing the open end of said cavity in both open and closed positions of said bits.

16. An underreamer, comprising a body member having a cavity at one end, swinging cutting bits located in said cavity, means for extending said bits, means for locking said bits in extended position, a transverse hinge pintle on which said bits are journaled, said pintle being removable through the side Walls of said cavity and thereby releasing the operating parts of the underreamer, and yielding means located between said pintle and bits for normallyholding- 18. An underreamer, comprising a body member having a cavity at one end thereof, hinged cutting bits located in said cavity, a rotatable locking device for said bits having locking and release positions, and gear members for rotating said locking device to release position.

19. An underreamer, comprising a body member having a cavity at one end thereof, hinged cutting bits located in said cavity, a

rotatable locking device for said bits having locking and release positions, gear members for rotating said locking. device to release position, and yielding means for moving said locking device to locking position.

In testimony whereof, I have hereunto set my hand.

JAMES F. CRAVEN. Witnesses:

GLENN H. LERESCHE, ELBERT L. HYDE.

Copies of this patent may be obtained for five cents each, by addressing the "Commissioner of Patents, Washington, D. G. 

